Disklavier

A Disklavier E3 connected to a home music system broadcasting on multiple zones only reproduces what you hear from the built-in speakers. However, we want to hear not only the vocals and accompaniment, but the actual piano as well. What is the best way to accomplish this? Via a pickup or transducer? If so, where does that output go?

This is for an E3 without the silent system.

Thanks,

Vince